1. Technical Field of the Invention
This invention relates to tolerance analysis, and more particularly, to a method of optimizing mechanical tolerances for designing and manufacturing components.
2. Description of Related Art
During initial production of products, many companies have quite a few quality and documentation problems. Many of the initial production problems fall into one of three categories: manufacturing, assembly fit, and design documentation. Manufacturing problems are particularly evident in the form of high scrap rates. To reduce these scrap rates, manufacturers often have to rework parts, add fixtures to current manufacturing processes, utilize different (and usually more expensive) processes, inspect more parts, and, of course, increase quality control testing of the products. Obviously, these measures can be quite expensive.
In regards to assembly fit problems, manufacturers oftentimes work around these problems by mixing and matching parts, modifying parts within the assembly area, sending the parts to another department or vendor for modification, or merely discarding the defective parts. However, the only permanent solution to assembly fit problems is to change the design and/or its manufacturing processes. Typically, scrapping an entire design and starting from scratch is cost prohibitive, and thus not normally done. Instead, design changes are made that minimize the impact on the costs. Normally, modification of designs are minimized, which usually means that the optimal solution is not used. Design fixes may include designing additional parts, adding adjustments to the design, adding or changing assembly processes, maintaining unique parts and tightening tolerances. However, these actions drastically increase recurring manufacturing costs and require the focus of design teams to be on ongoing production rather than developing new products.
Correcting these assembly and manufacturing deficiencies requires many documentation changes, which typically includes writing engineering changes to product drawings (e.g., changing dimensioning schemes, nominal dimensions, tolerances, variation controls, purchased parts, etc.), tooling drawings, and manufacturing process documents. Additionally, many changes are required to correct inappropriately applied variation controls that violate a dimensioning standard or do not control a feature as intended.
The cost for implementing fixes to these problems is both staggering and not completely effective. In addition, companies risk exposure to warranty and legal costs from mass-producing defective products. A methodology is needed that links mechanical assembly tolerancing requirements to part variation controls in order to improve the mechanical tolerancing process.
Thus, it would be a distinct advantage to have a system and method which provides a link between mechanical assembly tolerancing requirements and part variation controls. It is an object of the present invention to provide such a system and method.